Conformational changes in melittin upon complexation with an anionic melittin analog

AbstractMelittin and its Glu-(7,21,22,23,24) analog upon mixing in equimolar concentrations form a hybrid oligomer with significant helical structure, in conditions in which each peptide separately adopts a largely disordered structure. The hybrid exhibits both cold- and heat-induced denaturations similar to the phenomena exhibited by proteins. The hybrid also retains significant residual structure at higher temperature, similar to the ‘molten globular state’ that has been suggested for proteins. Melittin, at concentrations in which it forms helical tetramers, also exhibits these phenomena and may be used as a model for protein-denaturation studies

Endoscopic Management of Afferent Loop Syndrome after a Pylorus Preserving Pancreatoduodenecotomy Presenting with Obstructive Jaundice and Ascending Cholangitis

Afferent loop syndrome is a rare complication of gastrojejunostomy. Patients usually present with abdominal distention and bilious avomiting. Afferent loop syndrome in patients who have undergone a pylorus preserving pancreaticoduodenectomy can present with ascending cholangitis. This condition is related to a large volume of reflux through the biliary-enteric anastomosis and static materials with bacterial overgrowth in the afferent loop. Patients with afferent loop syndrome after pylorus preserving pancreaticoduodenectomy frequently cannot be confirmed as surgical candidates due to poor medical condition. In that situation, a non-surgical palliation should be considered. Herein, we report two patients with afferent loop syndrome presenting with obstructive jaundice and ascending cholangitis. The patients suffered from the recurrence of pancreatic cancer after pylorus preserving pancreaticoduodenectomy. The diagnosis of afferent loop syndrome was confirmed, and the patients were successfully treated by inserting an endoscopic metal stent using a colonoscopic endoscope

Solution structure of the DNA-binding domain of human telomeric protein, hTRF1

AbstractBackground: Mammalian telomeres consist of long tandem arrays of the double-stranded TTAGGG sequence motif packaged by a telomere repeat binding factor, TRF1. The DNA-binding domain of TRF1 shows sequence homology to each of three tandem repeats of the DNA-binding domain of the transcriptional activator c-Myb. The isolated c-Myb-like domain of human TRF1 (hTRF1) binds specifically to telomeric DNA as a monomer, in a similar manner to that of homeodomains. So far, the only three-dimensional structure of a telomeric protein to be determined is that of a yeast telomeric protein, Rap1p. The DNA-binding domain of Rap1p contains two subdomains that are structurally closely related to c-Myb repeats. We set out to determine the solution structure of the DNA-binding domain of hTRF1 in order to establish its mode of DNA binding.Results: The solution structure of the DNA-binding domain of hTRF1 has been determined and shown to comprise three helices. The architecture of the three helices is very similar to that of each Rap1p subdomain and also to that of each c-Myb repeat. The second and third helix form a helix-turn-helix (HTH) variant. The length of the third helix of hTRF1 is similar to that of the second subdomain of Rap1p.Conclusions: The hTRF1 DNA-binding domain is likely to bind to DNA in a similar manner to that of the second subdomain of Rap1p. On the basis of the Rap1p–DNA complex, a model of the hTRF1 DNA-binding domain in complex with human telomeric DNA was constructed. In addition to DNA recognition by the HTH variant, a flexible N-terminal arm of hTRF1 is likely to interact with DNA